DURHAM — One person was injured and traffic was backed up for more than two hours after a minivan slammed into the back of a tractor-trailer along Interstate 85 in Durham Wednesday morning.

Durham police say Barry J. Walker, 41, of Ridgeway, Va., was driving south on I-85 at a high rate of speed when his 1995 Ford Windstar van crashed into the back of a southbound tractor-trailer.

The driver of the tractor-trailer told police he was trying to merge left when the accident occurred at 6:46 a.m. near the N.C. 147 exit.

He says he tried to avoid a collision by pulling over to the shoulder. The van ran off the highway into the emergency breakdown lane and struck the back of the tractor-trailer.

The force of the crash drove the stopped the tractor-trailer 30 feet.

Emergency crews cut Walker from the wreckage and rushed him to nearby Duke Medical Center. He is listed in critical condition.

Officers said Walker may have been impaired by drugs, and high speed contributed to the accident. So far, no charges have been filed.